Frequently, broadband systems transmit television signals and programs to subscribers of a conditional access system. Broadband systems, such as cable and satellite television systems, typically include a headend for receiving programming and/or data from various sources and redistributing the programming and other data through a distribution system to subscribers. The headend receives programming signals from a variety of sources, combines the programming signals from the various sources, and transmits the combined signals through the distribution system to subscriber equipment. The distribution system can include a variety of media, such as coaxial cable, fiber optic cable, and satellite links. In a subscriber television system, the subscriber equipment, which receives the signals from the headend, can include a cable-ready television, a cable-ready video cassette recorder (VCR), or a digital subscriber communications terminal (DSCT) that is connected to a television, computer, or other display device.
The headend uses modulators to control the streams of data into the distribution system. Increasingly, the headend is receiving and transmitting programming in a digital format, for example, Moving Pictures Expert Group (MPEG) format, instead of an analog format. Transmitting programs in MPEG format is advantageous because multiple digitized programs can be combined and transmitted in, for example, 6 MHz of bandwidth, which is the same amount of bandwidth that is required to transmit a single analog channel or program, and in comparison to analog programs, MPEG or digitized programs provide a cleaner and sharper image and sound. Various error correction schemes enable the digital packets to be transmitted through a digital network with minimal distortion or error.
In theory, the packets of a digital program can be reproduced or copied without error. Thus, a subscriber of a digital subscriber network who receives a digital program can record the program and copy it, and the copy will be virtually identical to the original. Therefore, there exists concern about illegal copying or bootlegging of digital content. The operators of a digital subscriber network and the content providers want to provide the subscribers of the digital network with the programming and services desired by the subscribers, but the digital content owners want to prevent the subscribers from making and distributing bootleg copies of the digitized programs and services. Thus, there exists a need for an apparatus that protects the property interests of the digital content owners, while providing the subscribers with the desired digital content.